Majestic witnesses of time, forest trees have very many qualities. But their cousins of cities are not left out and are valuable allies for an increasingly urbanized society. On the occasion of the International Forest Day, France Nature Environment unveils some of the super-powers of trees ... significant assets that must inspire public policies for the return of trees in town.
Super power n ° 1: the trees protect us against air pollution
Do you know that in France, air pollution is the third cause of mortality? On its scale, the tree, like all plants, fight against this scourge. Trees produce oxygen by photosynthesis, capture co2 During their growth and set many atmospheric pollutants.
Several studies have confirmed that trees in the city were able to absorb about half of the finest particles, which are also among the most harmful for our lungs. But it is not enough to plant any tree anywhere, because according to the species or its conditions of implantation (sunshine, wind, risk of drought ...), the effect of a tree on pollution can in some cases be questioned or even prove to be counterproductive1 Since it can sometimes emit volatile organic compounds, one of the air pollutants.
However, some species play a vital role against pollution2 provided they take into account their needs, their (many) qualities and their (small) defects. If in the face of Air pollution, France Nature Environnement promotes primarily a reduction in emissions, the preservation of trees and natural elements that reduce this scourge is not to neglect
Super power n ° 2: much better than air conditioning, trees fight against the islands of heat in the city
Climate change could cause an average increase in cities of 7 ° C1. Faced with these risks of strong poles, the tree is, again, a precious ally. Indeed, buildings and floors, so-called waterproof surfaces, concentrate heat in summer, which generates heat islands. The trees can absorb some of this heat and make the temperatures of the city more bearable. Thus, in Lyon, A study has demonstrated That "urban woodlands are 2 to 8 ° C coolest than the rest of the city".
This super power is due to the phenomenon of transpiration of plants. To balance the amounts of water and energy coming from solar radiation in their tissues, they reject water into the air and thus decrease the ambient temperature of a few degrees. Far from marginal, this phenomenon is the second largest element of the water cycle, after the rain.
France Nature Environnement emphasizes and trees have a double profit facing climate change. On the one hand, they store carbon responsible for this disturbance and the other, they make it possible to mitigate the effects of the guns, one of the manifestations of climate change.
Super power # 3: trees, road safety auxiliaries
Long designated as road safety goats, roadside trees have many assets to reduce accidents. The experience conducted in 2010 by the Norfolk English County authorities is particularly illuminating. As we approach the villages, tree alignments less and less spaced as well as "funnel plantations", more and more close to the road have made it possible to give a speed illusion. Result: motorists slow down and county authorities have observed a 20% reduction in the number of accidents.
To this experience is added Studies showing That these tree paths are visual benchmarks, very useful at night or when the weather is capricious (rain, fog). They also have a role of absorption of runoff, which prevents rainwater from stagnating on the road. Thanks to their shadows, they also decrease the temperature of the asphalt, essential in summer to avoid overheating1 But also avoid optical illusions that tire our eyes.
If it is true that in case of accident, a shock against a tree can be dramatic, the source of the accident is never the tree in itself but the speed, the alcohol, the Fatigue or the use of the mobile phone. These road flight trees make it possible to combat some of these accident sources. So enjoy their benefits instead of making bad trials.
1 This is why Napoleon, well before the advent of automobiles, has decided that trees should be planted at the edge of the ways borrowed by its soldiers, to benefit from their shading and arriving "fees and disposable" on the battlefield.
Super power n ° 4: woodland and forest spaces, champions to relax
Wood of Vincennes in Paris, wood of the epau at Le Mans, Park of the Golden Head in Lyon ... Many cities have a wooded park or better, a wood, a forest. Much more pleasant than a picnic on a parking lot, the exit in a wooded area offers a place of greenery that participates in the happiness of the inhabitants of these cities. The beauty of the trees and the prospects they offer go beyond, amaze us and contribute to our well-being.
Let's add to that time, decades necessary for a young shoot to reach more than 60 m high (records in France1), and we obtain places champions of the reception of the public, privileged spaces to reconnect to nature and use its five senses (with precaution, however, for taste and touch).
For France Nature Environnement, if woodland and forest spaces are home to many leisure activities, the key is to find the right balance between our presence and the needs of tranquility of species that live there ... because they are numerous.
1 On the podium of the highest trees in France: a Douglas (non-native) of 67 m, a sequoia (non-native) of 58 m, and a common epicéa (indigenous) of 56 m.
Super Power # 5: Trees, Wood and Forests, Biodiversity Refuges
Are you close to trees, in a wood or forest? Open your eyes and hold the ear to see one of the magnificent super-powers of the trees: they welcome more than 80% of terrestrial biodiversity. The diversity of tree essences, the presence of very old trees and carriers of microhabitats (cavities, slits, sides of Sèves ...) are beneficial to the whole forest ecosystem.
This heterogeneity hosts a wide variety of plants, mushrooms, animals, which in turn make the trees more resistant and the less fragile ecosystem facing diseases or climate events (storms, droughts ...). All reports and scientific studies confirm: we can not stop deforestation, species disappear at a vertiginous speed, yet the laws are more interested in the volumes of wood than the forest, the need to preserve their functioning and their biodiversity. A change of course is more than necessary for a liveable world, replacing the tree and the many services it returns to society on the front of the stage. On a daily basis, France Nature Environnement promotes and defends this vision within the many commissions and instances to which it participates, because the trees have so much to bring them that they deserve much more than a day!